The one doctrine universally held in the seventeenth century by every Protestant church, from the highest of high church Anglicans to the wildest of the Anabaptist of Fifth Monarchy sects, was the identification of the papacy with the antichrist. This doctrine was inserted into the Westminster Confession of Faith, chapter 25, section 6, to the embarrassment of modern American Presbyterians, who have seen fit to footnote this passage into oblivion, and quite properly so.
My two cents
I’ve seen several websites accusing the Pope or Barack Obama of being the antichrist, and I think this is fraught with danger. The Bible says that if you accuse someone, and your accusation is false, your penalty as the false accuser is the same as if the accused was found guilty (Deuteronomy 19:16-19).
I’ve heard the penalty for the antichrist is to be thrown into the lake of fire. Therefore, if you accuse someone of being the antichrist—and they’re not—then your punishment could be the lake of fire as well.
I’ve done a bit of conflation, but even so, there’s no way I’d risk accusing someone of being the antichrist (Deuteronomy 19:16-20).
North, G (1978), “Family Authority Versus Protestant Sacredotalism” in The Journal of Christian Reconstruction, vol. 4, no. 2, p. 114